/*
 * Srm 186 div 1 prob 3
 */

import java.util.*;
import java.util.regex.*;
import java.text.*;
import java.math.*;


public class PuckShot
{
    int h = 1733;
    int w = 3000;
    int p;
    
    double getOff (int x, int y) {
	return p - (double)h*(p-x)/y;
    }
    
    
    public double caromAngle(int pp, int[] x1, int[] y1)
    {
	int n = x1.length;
	p = 2*w - pp;
	
	double l = 1500-91.5, u = 1500+91.5;
	
	ArrayList<Double> all = new ArrayList<Double> (), alu = new ArrayList<Double> ();
	for (int i = 0; i < n; ++i) {
	    double tmpl = getOff (x1[i]-25, y1[i]), tmpu = getOff (x1[i]+25, y1[i]);
	    if (!(tmpu <= l || tmpl >= u)) {
		if (tmpl <= l)
		    tmpl = l;
		if (tmpu >= u)
		    tmpu = u;
		all.add (tmpl);
		alu.add (tmpu);
	    }
	    
	    x1[i] = 2 * w -x1[i];
	    tmpl = getOff (x1[i]-25, y1[i]);
	    tmpu = getOff (x1[i]+25, y1[i]);
	    if (!(tmpu <= l || tmpl >= u)) {
		if (tmpl <= l)
		    tmpl = l;
		if (tmpu >= u)
		    tmpu = u;
		all.add (tmpl);
		alu.add (tmpu);
	    }
	}
	
	/* Check. */
	double ans = -1;
	
	for (int i = 0; i < all.size (); ++i) {
	    double curl = all.get (i);
	    boolean check = true;
	    /* check curl. */
	    if (curl == l || curl == u) 
		check = false;
	    for (int j = 0; j < all.size (); ++j) {
		if (i == j) continue;
		if (curl >= all.get (j) && curl <= alu.get (j)) {
		    check = false;
		    break;
		}
	    }
	    if (check)
		ans = Math.max (ans, curl);
	    check = true;
	    curl = alu.get (i);
	    /* check curl. */
	    if (curl == l || curl == u) 
		check = false;
	    for (int j = 0; j < all.size (); ++j) {
		if (i == j) continue;
		if (curl >= all.get (j) && curl <= alu.get (j)) {
		    check = false;
		    break;
		}
	    }
	    if (check)
		ans = Math.max (ans, curl);
	}
	
	/* Check u. */
	boolean check = true;
	for (int i = 0; i < all.size (); ++i) {
	    if (u == alu.get (i)) {
		check = false;
		break;
	    }
	}
	if (check)
	    ans = u;
	
	if (ans == -1)
	    return -1.0;
	return Math.toDegrees (Math.atan (h/(p-ans)));
	
    }
    

}
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